This invention relates to a pressure relief valve which may be used as a single stage valve or as a pilot valve for a two-stage pressure control valve. The invention also has particular, but not exclusive, reference to a proportional pressure relief valve and is also applicable either to pneumatic or hydraulic valves.
Known pressure relief valve suffer the problem of instability which manifests itself as a physical oscillation of the valve closure member or poppet. It is an object of the present invention to provide a more stable pressure relief valve with low pressure/control current hysteresis.